Missed last week 'cause of holidays, but this week's theme is libraries that make documentation easier. Like testing, documentation also comes in 3 main flavors: user, developer, and doctests.

User

These are the tutorials, how-to manuals, screencasts, etc.-the stuff that tells users how to use the product. For a software library, this is setup, install, and the API, whereas for a website like facebook, this will explain new settings and how to change a picture.

Dev

These are the APIs and implementation details that tell devs how to build something with or similar to the product. API docs are dev docs for facebook and twitter and the like because they're being used to build tools on top of the platform that users are using. On the otherhand, devs are the user for a framework or library, so in those cases, dev docs would discuss how the library was built and how to add new functionality into the libary. Dev docs can also discuss the various technologies used in building and running the platform.

Doctests

A hybrid between user documentation and testing, doctest libaries search for documentation that looks like an interactive shell session and executes it to verify that running that code will get that session.

Rules:

1.
Please form your responses with: [Language] Library Name that links to
the library's homepage or archive (PiPy/CRAN/CTAN/etc.) listing - what
the library does and why you're recommending it.2. Documentation library only please. Do you wanna share something else? Suggest next weeks theme in the comments.3. You can choose whatever language you like: Python, Javascript, Java, Prolog, Haskell, SQL, x86 assembly, Piet, any of the zillions not listed here, etc.

Example:

[Javascript] autodoc
- JS library for writing doctests and benchmarks. Auto generates documentation based on the comments and has a command line tool for running tests/benchmarks from the comments.